[Sync] Refactor non-frontend DTC to handle new API properly.

chrome/browser/sync/glue/non_frontend_data_type_controller.cc

Index: chrome/browser/sync/glue/non_frontend_data_type_controller.cc
diff --git a/chrome/browser/sync/glue/non_frontend_data_type_controller.cc b/chrome/browser/sync/glue/non_frontend_data_type_controller.cc
index 8897b69e39873ea1149645a6a4b202e595056254..c1cc49d47790e2e9dea646e6fd5e1f784713d24c 100644
--- a/chrome/browser/sync/glue/non_frontend_data_type_controller.cc
+++ b/chrome/browser/sync/glue/non_frontend_data_type_controller.cc
@@ -60,8 +60,7 @@ void NonFrontendDataTypeController::Start(StartCallback* start_callback) {
   state_ = MODEL_STARTING;
   if (!StartModels()) {
     // If we are waiting for some external service to load before associating
-    // or we failed to start the models, we exit early. state_ will control
-    // what we perform next.
+    // or we failed to start the models, we exit early.
     DCHECK(state_ == NOT_RUNNING || state_ == MODEL_STARTING);
     return;
   }
@@ -116,7 +115,7 @@ void NonFrontendDataTypeController::StartAssociation() {
   }
 
   profile_sync_service_->ActivateDataType(type(), model_safe_group(),
-                                          change_processor_.get());
+                                          change_processor());
   StartDone(!sync_has_nodes ? OK_FIRST_RUN : OK, RUNNING, SyncError());
 }
 
@@ -153,6 +152,12 @@ void NonFrontendDataTypeController::StartDoneImpl(
     DataTypeController::State new_state,
     const SyncError& error) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  if (state_ == NOT_RUNNING) {
+    // Already stopped. just return.
+    DCHECK(!start_callback_.get());
+    return;
+  }
+  DCHECK(start_callback_.get());
   state_ = new_state;
   if (state_ != RUNNING) {
     // Start failed.
@@ -167,9 +172,9 @@ void NonFrontendDataTypeController::StartDoneImpl(
   callback->Run(result, error);
 }
 
-// TODO(sync): Blocking the UI thread at shutdown is bad. If we had a way of
-// distinguishing chrome shutdown from sync shutdown, we should be able to avoid
-// this (http://crbug.com/55662).
+// TODO(sync): Blocking the UI thread at shutdown is bad. The new API avoids
+// this. Once all non-frontend datatypes use the new API, we can get rid of this
+// locking (see implementation in AutofillProfileDataTypeController).
 void NonFrontendDataTypeController::Stop() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   // If Stop() is called while Start() is waiting for association to
@@ -272,15 +277,27 @@ ProfileSyncService* NonFrontendDataTypeController::profile_sync_service()
   return profile_sync_service_;
 }
 
+void NonFrontendDataTypeController::set_start_callback(
+    StartCallback* callback) {
+  start_callback_.reset(callback);
+}
 void NonFrontendDataTypeController::set_state(State state) {
   state_ = state;
 }
 
+AssociatorInterface* NonFrontendDataTypeController::associator() const {
+  return model_associator_.get();
+}
+
 void NonFrontendDataTypeController::set_model_associator(
     AssociatorInterface* associator) {
   model_associator_.reset(associator);
 }
 
+ChangeProcessor* NonFrontendDataTypeController::change_processor() const {
+  return change_processor_.get();
+}
+
 void NonFrontendDataTypeController::set_change_processor(
     ChangeProcessor* change_processor) {
   change_processor_.reset(change_processor);